In recent years, an increase in the number of servers makes the complexity associated with the operation increase, as a result of which there arises a problem of an increase in the operation costs. As a technique that reduces the operation costs, attention is focused on a server consolidation that consolidates plural servers into one.
As one of techniques that realize the server consolidations, there has been known a virtual machine that logically divides one computing machine at an arbitrary rate. In the technique, a firmware (or middleware) such as a hypervisor allows a physical computing machine to be divided into plural logical partitions (LPAR), a computing machine resource (CPU, main memory, I/O) is allocated to each of the LPARs, and an OS is operated on each of the LPARs (for example, JP 2002-304364A).
Also, there has been known a technique by which plural guest OSs are operated on a host OS, and the respective guest OSs are provided as the logical partitions as in VMware (registered trademark).
Further, in recent years, there has been known a technique by which the construction of an I/O sub-system is more flexibly re-configured by a blade server that is capable of changing the configuration of computing machine on a baseboard basis. Furthermore, a server consolidation that consolidates a large number of servers into a blade server is conducted.
Also, in recent years, there has been proposed an I/O switch that is represented by an AS (advanced switching) (for example, “Advanced switching technical summary”). The I/O switch of this type realizes a shared I/O card (or I/O device) from plural CPUs (physical CPUs). The AS is high in the versatility because there can be used the I/O device (or I/O card) of the PCI-EXPRESS standards which is presently spreading.
In the shared I/O between the respective logical partitions due to the VMware, because the logical partitions cannot be identified on the I/O device side, it is necessary that the I/O requests of the respective logical partitions are centrally-managed and given to the physical I/O device. For that reason, when the host OS centrally controls the I/O operation, thereby realizing the shared I/O device between the respective logical partitions which are constructed by the guest OSs. As a result, the I/O requests from the respective logical partitions are conducted on the physical I/O device after waiting for the processing of the host OS once. Therefore, there arises such a problem that the processing of the host OS becomes overhead, and a response of the I/O is lowered.
In the above hypervisor, a specific I/O device (a channel) which is capable of being aware of the logical partitions is used to share the I/O between virtual machines. The I/O device conducts the I/O operation while being aware of the partitions, and is capable of directly accessing to the I/O device from the respective logical partitions. However, because the special I/O device is required, there arise such problems that the manufacturing costs are high, and the versatility is low.
On the other hand, in the case where the I/O switch such as the advanced switching is used in the above conventional hypervisor to share the I/O device between the logical partitions, there occurs the following problems.
Because the above advanced switching (hereinafter referred to simply as “AS”) is capable of identifying nothing other than a physical node (or device), the AS is incapable of identifying the logical partitions that are provided by the hypervisor, and the AS as it is cannot be applied to the above hypervisor. For that reason, software that centrally controls the I/O operation of the AS is required as in the above VMware, which leads such a problem that the processing of the software operation itself becomes the overhead of the I/O access.